I keep a modest collection of many useful types of cores that I bought from
Amidon, from their excellent complete Catalog. The initial expense was a
couple of hundred dollars about 15 years ago, but I know exactly what I
have, and I save a lot of time and trouble. When I run low on some type I
order replacements. I store them in plastic zipper bags with labels. For
home experimenting it is a very good way to go. I also have an ancient
Boonton Q meter and an ancient surplus HP Vector Impedance Meter.

Bill W0IYH

"dave" wrote in message
...
Hi all,

Is there an easy way to test surplus toroids as to what mix they might be?
I have some here with no markings (plain black powder) and I would like to
see what frequency ranges they would be useful at. I guess I would have
to
wind up a transformer and plot the frequency response?

Dave